A standard piston-type pressure accumulator has a cylinder forming a chamber that is subdivided into a gas compartment and a liquid compartment by a piston which is movable to increase the volume of one of the compartments while decreasing that of the other and vice versa. The gas compartment is filled with a gas under pressure, usually compressed air, and the liquid compartment is connected to the hydraulic system whose pressure is to be maintained.
Normally a passage provided with a check valve opens directly into the gas compartment and serves for charging same. A screw connection permits the charging equipment to be connected to this passage. Such construction is fairly complex and therefore elevates the cost of the accumulator.